Recently, a high solid coating composition comprising crosslinked polymer microparticles dispersed in a conventional coating composition containing film-forming resinous vehicle, has been watched with keen interest in various coating areas and especially in an automobile industry, because of the eminent workability and capability of obtaining a coating with excellent film properties. These particles are composed of polymer crosslinked to the extent that it is insoluble in an organic solvent in which the particles are dispersed, finely pulverized to micron size, and stably dispersed in the coating composition. Dispersion of said microparticles in a solvent or a carrying vehicle is often called, for convenience, as "microgels". However, when microgel particles and coating resinous vehicle are lacking in mutual affinity, there are such problems that thus obtained coating composition will generate precipitations through agglomeration of said microgel, during storage and there give troubles in gloss and smoothness of the resulted coating likewise through agglomeration of microgel particles in both coating and drying steps. Employment of an emulsifier or dispersing agent will obviate said agglomeration, but it will cause additional problems of poor qualities of the formed coating such as water proofness and the like.
Attempts have therefore been made to settle the abovementioned problems, to get a far stabilized dispersion of polymer microparticles in resinous vehicle with the help of various specific type emulsifiers; however, no satisfactory solutions have been found yet. Under the circumstances, it would be an immeasurable advancement of the technical level concerned if one could provide a highly stabilized dispersion of microgel particles in a resinous vehicle without relying on a specific type of emulsifier and provide a high solid coating composition based on said dispersion, which is excellent in storage stability and capable of resulting in a coating with excellent gloss and improved appearance.